The Launch Region of the SVS13 Outflow
Klaus W. Hodapp
University of Hawaii, Institute for Astronomy
Abstract
[FeII] Jet Rotation
We present the results of Keck Telescope laser adaptive optics integral field spectroscopy with
OSIRIS of the innermost regions of the NGC1333 SVS13 jet that drives the system of Herbig-Haro
objects 7-11. We find a 0.4˝ long micro-jet traced by the emission of shock-excited [FeII]. Beyond
the extent of this jet, we find a series of near-spherical bubbles traced in the lower excitation H2
1–0 S(1) line. While this most recent outflow activity is directed almost precisely (PA 170°) to the
south of SVS13, the older bubbles show a different direction of motion and orientation more
towards the south-east, connecting the recent outflow activity to the well-known, poorly
collimated HH 7-11 system of Herbig-Haro objects. We postulate that the creation of a series of
bubbles and the changes in outflow direction are indicative of a precessing disk. Our velocityresolved observations of the microjet in the [FeII] emission line at 1.644µm, as well as the HI12-4
and 13-4 (Brackett series) emission lines originating from the accretion disk or jet launch region
clearly show the kinematic signature of disk and jet rotation.
Fig. 6: Continuum-subtracted [FeII] 1.644µm
images of the SVS13 jet, original on the right
and deconvolved using the Lucy-Richardson
algorithm on the left. The bottom panel
shows the centroid velocity for each spaxel
in the deconvolved image in a color-coded
representation. It clearly shows that all the
line emission from the jet is blue-shifted
relative to the systemic velocity of SVS13.
On top of the dominant blue-shift, the
eastern edge of the jet is relatively redshifted while the western edge is relatively
blue-shifted.
Observations
The adaptive optics data in the H and K bands reported here were obtained at the Keck I and II
telescopes in 2011 and 2012, using laser guide star adaptive optics with the OSIRIS integral field
spectrograph (Larkin et al. 2006). The resulting data cubes contain the atomic hydrogen 12-4
(1.641µm) and 13-4 (1.611µm) Brackett lines, the shock-excited [FeII] 1.644µm line, and the lowexcitation shock-excited H2 1-0 S(1) line at 2.122µm. Outside of emission lines, SVS13 appears as
an unresolved source. Continuum images of SVS13 were used as the PSF for Lucy-Richardson (Lucy
1974) deconvolution of the data.
This is the characteristic pattern of jet
rotation in addition to the jet motion.
Morphology
Indications of Disk Rotation
Fig. 7: The individual panels in the top part
show every other of the Lucy-Richardsondeconvolved
and
continuum-subtracted
images of the Brackett 13 (left) and Brackett
12 (right) emission. The centroid of the
continuum component of each image is
indicated by a star. For each spaxel in the
deconvolved image, the centroid of the
velocity was computed and averaged over
the two lines. The panels cover 24×24AU.
The result is shown in the lower (color) panel
and clearly indicates a shift in the velocity
centroid across the line emission in a
direction
perpendicular
to
the
jet
orientation.
Fig. 1: Zooming towards SVS13: The
SVS13 (Strom, Vrba, Strom, 1976)
outflow at different spatial scales in
K band, from seeing-limited (top) to
the OSIRIS H2 S(1) image (bottom).
This is the expected kinematic signature of
a rotating accretion disk.
Fig. 2: Color Composite of the SVS13 jet and bubble,
based on the deconvolved OSIRIS data cubes. Green is
[FeII] and red is H2 S(1). A scaled down continuum image
of the stellar object SVS13 was added to show its
position. At the distance of SVS13 of 235pc (Hirota et al.
2008), the bubble has a diameter of 95AU.
Molecular Hydrogen S(1) Line Kinematics
Fig. 3 (left) and Fig. 4 (above): Velocity channels (relative to the
SVS13 systemic velocity) of the H2 S(1) line emission (left Figure). The
position of the two slits where the position-velocity diagrams in the
top figure were derived are indicated. The bubble is a thin shell with
emission from the front surface being visible, but with no emission
from the receding (red-shifted) back surface being detectable.
Fig. 5: The left panels show the integrated 2.122µm line
image from 2011 Aug. 21, the right panels show the same
line on 2012 Nov. 4. Both images were scaled to
1mas/pixel and registered on the unresolved image of the
stellar source SVS13. The black circles in the top panels
are the best visual fit of a circle to the image of the
bubble. The green circle in the 2011 image (left panel)
shows the fitting circle in 2012, while the red circle in the
2012 image (right panel) shows the fit to the 2011 data.
These lower panels demonstrate clearly that a significant
motion and expansion of the bubble has occurred over the
441 days separating the epochs of these images.
Conclusions
• The HH7-11 outflow, at present, originates from SVS13 as a micro-jet of ~0.4˝ length, detectable
in [FeII] and oriented at P.A. 170° (Fig. 2).
• From the driving source to the first bubble, the [FeII] emission traces a nearly straight micro-jet.
Beyond that, the H2 S(1) emission outlines a curved path of the jet (Fig. 2).
• This present jet orientation is consistent with the orientation of outflowing material in the
counter-jet found by Bachiller et al. (2000) in CO.
• An instability in the [FeII] microjet has generated an internal shock front that manifests itself as
an expanding, moving bubble seen in H2 S(1) emission (Fig.1,2,3).
• The formation of this bubble can be traced back to the ~1990 “EXor” outburst of SVS13 reported
by Eislöffel et al. (1991) (Fig. 5).
• Recent K-band photometry (not shown here) indicates that this outburst is not over, but that
SVS13 remains substantially above its pre-outburst brightness.
• Two other, older bubbles have been unambiguously observed whose orientation indicates that
past internal shock fronts have propagated in slightly different directions closer to the 123° P.A.
of the HH7-11 chain of Herbig-Haro objects (Davis et al. 2001). This indicates precession of the
accretion disk and driving jet (Fig. 1).
• A clear velocity gradient, interpreted as the signature of jet rotation, is detected along the first
200 mas of the micro-jet (47 AU). Beyond this, at the point where the [FeII] jet interacts with the
expanding H2 S(1) bubble, the rotation signature becomes confused (Fig. 6).
• Atomic Hydrogen emission in the HI12-4 and HI13-4 (Brackett series) lines is detected around the
continuum position of SVS13 and shows the kinematic signature of accretion disk rotation (Fig. 7).
References
Bachiller, R., Gueth, F., Guilloteau, S., Tafalla, M., Dutrey, A. 2000, AAP, 362, L33
Davis, C. J., Ray, T. P., Desroches, L., & Aspin, C. 2001, MNRAS 326, 524
Eislöffel, J., Gϋnther, E., Hessman, F.~V., Mundt, R., Poetzel, R., Carr, J. S., Beckwith, S., & Ray, T. P. 1991, APJL, 383, L19
Hirota, T., Bushimata, T., Choi, Y. K. et al. 2008, PASJ, 60, 37
Larkin, J., Barczys, M., Krabbe, A., et al. 2006, Proceedings SPIE, 6269, 42
Lucy, L. B. 1974, AJ, 79, 745
Strom, S. E., Vrba, F. J, & Strom, K. M. 1976, AJ, 81, 314
Contact Address:
Klaus Hodapp, University of Hawaii, Institute for Astronomy, 640 N. Aohoku Place, Hilo, HI 96720, USA
Email: [email protected]
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